Bezel-less Acoustic Touch Apparatus

ABSTRACT

An acoustic touch apparatus is provided that includes a substrate capable of propagating surface acoustic waves, such as Rayleigh-type or Love-type waves. The substrate has a front surface, a back surface, and a curved connecting surface formed between the front surface and the back surface. The apparatus also includes at least one acoustic wave transducer and at least one reflective array, the acoustic wave transducer and the reflective array behind the back surface of the substrate. The acoustic wave transducer is capable of transmitting or receiving surface acoustic waves to or from the reflective array. The reflective array is capable of acoustically coupling the surface acoustic waves to propagate from the back surface and across the front surface via the curved connecting surface. Various types of acoustic touch apparatus with edge sensitive touch functions can be provided, according to specific embodiments.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of, and claims priority to,U.S. patent application Ser. No. 12/732,132 filed on Mar. 25, 2010.

FIELD OF THE INVENTION

The present invention relates to the field of acoustic touch sensorsystems, and more particularly to surface acoustic wave touch screens,touch monitors or touch computing devices.

BACKGROUND

Touch sensor systems, such as touch screens or touch monitors, can actas input devices for interactive computer systems used for applicationssuch as information kiosks, computers, order entry systems forrestaurants, video displays or signage, mobile devices, etc. Touchsensor systems or touch screens may be integrated into a computingdevice, thus providing interactive touch capable computing devices,including computers, video displays or signage, or mobile devices.

The dominant touch sensor technologies are resistive, capacitive, andacoustic. Acoustic touch sensors, such as ultrasonic touch sensors usingsurface acoustic waves, are particularly advantageous when theapplication demands a very durable touch sensitive surface and minimaloptical degradation of the displayed image.

Many types of acoustic touch sensors exist. For example, one type ofacoustic touch screen includes a touch substrate having an array oftransmitters positioned along a first peripheral surface of a substratefor simultaneously generating parallel surface bound or plate waves thatdirectionally propagate through the panel to a corresponding array ofdetectors positioned opposite the first array on a second peripheralsurface of the substrate. Another pair of transducer arrays is providedon the substrate surface at right angles to the first set. Touching thesubstrate surface at a point causes an attenuation of the waves passingthrough the point of touch, thus allowing interpretation of an outputfrom the two sets of transducer arrays to indicate the coordinates ofthe touch. This type of acoustic touch position sensor is shown in WO94/02911 (Toda), incorporated herein by reference.

Another example of an acoustic touch sensor system, termed theAdler-type acoustic touch screen, efficiently employs transducers, byspatially spreading the signal and analyzing temporal aspects ofperturbation as indicative of position. A typical rectangular touchscreen thus includes two sets of transducers, each set having adifferent axis aligned respectively with the axes of a physicalCartesian coordinate system defined by a substrate. An acoustic pulse orpulse train is generated by one transducer, propagating as, e.g., anarrow Rayleigh wave along an axis which intersects an array ofreflective elements, each element angled at 45° and spaced correspondingto an integral number of wavelengths of the acoustic wave pulse. Eachreflective element in the array reflects a portion of the wave along apath perpendicular to the axis, across a broad touch region on the frontsurface of a substrate adapted for touch sensing, to an opposingreflective array and transducer which is a minor image of the firstarray and transducer, while allowing a portion to pass to the nextreflective element of the array. The transducer of a minor image arrayreceives an acoustic wave consisting of superposed portions of theincrementally varying wave portions reflected by the reflective elementsof both arrays, directed antiparallel to the emitted pulse. The acousticwaves are thus collected, while maintaining the time dispersioninformation which characterizes the coordinate position from which anattenuated wave originated. Wave paths in the active region of thesensor have characteristic time delays, and therefore a wave path orwave paths attenuated by an object touching the touch sensitive regionmay be identified by determining a timing of an attenuation in thecomposite returning waveform. A second set of arrays and transducers areprovided at right angles to the first, and operate similarly. Since theaxis of a transducer corresponds to a physical coordinate axis of thesubstrate, the timing of an attenuation in the returning wave isindicative of a Cartesian coordinate of a position on the substrate. Thecoordinates are determined sequentially to determine the two dimensionalCartesian coordinate position of the attenuating object. The systemoperates on the principle that a touch on the surface attenuates surfacebound or plate waves having a power density at the surface. Anattenuation of a wave traveling across the substrate causes acorresponding attenuation of waves impinging on the receive transducerat a characteristic time period. Thus, the controller need only detectthe temporal characteristics of an attenuation to determine thecoordinate position. Measurements are taken along two axes sequentiallyin order to determine a Cartesian coordinate position. It is also knownto take advantage of acoustic wave guiding effects to reduce borderwidths in Adler-type touch screens. See, U.S. Pat. Nos. 4,642,423;4,644,100; 4,645,870; 4,700,176; 4,746,914; Re. 33,151; and 6,636,201;each incorporated herein by reference.

These examples of acoustic touch systems typically have a large numberof operative elements (either multiple transducers, or a transducer andreflective array) disposed on, and along, the surface of the substrate.In order to prevent damage due to exposure from the environment orexternal objects, these peripheral operative elements are hidden andprotected by a bezel provided over these elements on the front surfaceof the substrate and sealed, so that only the active touch region on thesurface of the substrate is exposed for possible touch input. Thesetypes of acoustic touch systems also are limited to processing touchinputs only for the active touch region, which is the part of thetransparent touch sensor that is overlying the display under the touchsensor.

In the commercial market for touch system devices, the cosmetic look ofthe devices as well as the robustness and reliability of featurecapabilities of such devices is becoming increasingly important. Variousattempts have been made, for example, to minimize the size of the bezelon the periphery of the touch screen in such devices. However, touchdevices conventionally still have had a bezel on the front of thedevice, although the bezel may have been reduced in profile and/or had athinner border width.

Therefore, it is desired to have bezel-less acoustic touch systems thatprovide additional touch function features beyond those provided in theactive touch region.

SUMMARY OF THE INVENTION

According to a specific embodiment, the present invention provides anacoustic touch apparatus. The apparatus includes a substrate capable ofpropagating surface acoustic waves. The substrate has a front surface, aback surface, and a curved connecting surface formed between the frontsurface and the back surface. The device also includes at least oneacoustic wave transducer and at least one reflective array. The acousticwave transducer and reflective array are behind the back surface of thesubstrate. The acoustic wave transducer is capable of transmitting orreceiving surface acoustic waves to or from the reflective array. Thereflective array is capable of acoustically coupling the surfaceacoustic waves to propagate from the back surface and across the frontsurface of the substrate via the curved connecting surface.

For a full understanding of this and other embodiments of the presentinvention, reference should now be made to the following detaileddescription of the various specific embodiments of the invention asillustrated in connection with the accompanying drawings, which are notto scale.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified cross-sectional view of an acoustic touch sensoror touch screen, according to a specific embodiment of the invention;

FIG. 2( a) and FIG. 2( b), respectively, are front and back views of thesubstrate of an acoustic touch sensor, according to a specificembodiment;

FIG. 3( a), FIG. 3( b) and FIG. 3( c) are cross-sectional partial viewsof differently curved connecting surfaces of the substrate of acoustictouch sensors, according to various specific embodiments;

FIG. 3( d), FIG. 3( e) and FIG. 3( f), respectively, are experimentalmeasurements illustrating the performance of surface acoustic wavestraveling over the differently curved connecting surfaces of FIG. 3( a),FIG. 3( b) and FIG. 3( c);

FIG. 3( g) is a cross-sectional partial view of an improperly processededge of a substrate of an acoustic touch sensor manufactured with agrinding tool 17 that may be used in accordance with a specificembodiment of the invention;

FIG. 3( h) is a cross-sectional partial view of a processed edge of asubstrate of an acoustic touch sensor manufactured with a grinding tool18 that may be used in accordance with another specific embodiment ofthe invention;

FIG. 3( i) and FIG. 3( j) are cross-sectional partial views ofdifferently configured curved connecting surfaces of the substrate ofacoustic touch sensors, according to further specific embodiments;

FIG. 4 is a simplified cross-sectional view of an acoustic touch device,according to another specific embodiment;

FIG. 5 is an exploded perspective view of an acoustic touch deviceaccording to a specific embodiment;

FIG. 6( a) and FIG. 6( b), respectively, are a partial cross-sectionalview and a partial plan view of a corner configuration and mountingscheme for a bezel-less acoustic touch device, according to a specificembodiment;

FIG. 6( c) illustrates a cross-sectional partial view of another cornerconfiguration and mounting scheme for a bezel-less acoustic touchsensor, according to another specific embodiment;

FIG. 6( d) is a front view of a bezel-less acoustic touch sensorprovided as part of another system such as a kiosk system, according tospecific embodiments;

FIG. 6( e) illustrates a partial cross-sectional slice perspective viewsof a sealing scheme for a bezel-less acoustic touch sensor shown justprior to flush mounting as part of another system such as a kiosksystem, according to a specific embodiment;

FIG. 6( f) illustrates a partial cross-sectional slice perspective viewsof a mounting scheme for a bezel-less acoustic touch sensor shownmounted as part of another system such as a kiosk system, according tothe embodiment of FIG. 6( e);

FIG. 6( g) and FIG. 6( h) illustrate partial cross-sectional sliceperspective views of two other mounting schemes for a bezel-lessacoustic touch device shown mounted as part of another system such as akiosk system, according to other specific embodiments;

FIG. 7 is a perspective view of a bezel-less acoustic touch device, likea touch monitor, with edge sensitive touch functions, according tospecific embodiments;

FIG. 8( a) and FIG. 8( b), respectively, are front and back views of thesubstrate of an acoustic touch sensor, according to another specificembodiment;

FIG. 9( a) and FIG. 9( b), respectively, are front and back views of thesubstrate of an acoustic touch sensor, according to yet another specificembodiment;

FIG. 10( a) and FIG. 10( b), respectively, are front and back views ofthe substrate of an acoustic touch sensor, according to still yetanother specific embodiment;

FIGS. 11( a) and 11(c), and FIGS. 11( b) and 11(d), respectively, arefront and back views of the substrate of an acoustic touch sensor,according to another specific embodiment;

FIG. 12( a) and FIG. 12( b), respectively, are front and back views ofthe substrate of an acoustic touch sensor, according to yet furtherspecifics embodiment;

FIG. 12( c) is a magnified partial plan view of a corner of the backsurface of the substrate of the acoustic touch sensor according to aspecific embodiment associated with FIGS. 12( a) and 12(b); and

FIG. 13 is a graph plotting wave velocity of the acoustic touch sensoras a function of the thickness of the acoustically benign layeraccording to a specific embodiment.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

The present invention provides a touch sensor apparatus, which may be atouch screen or other touch sensor or touch device (such as a touchcomputer, touch display or signage, or mobile touch device) in which anacoustic transducer, e.g., a piezoelectric element, is used to produce a“surface acoustic wave”, which is used herein to mean a Rayleigh-typewave, Love-type wave, or other surface bound acoustic wave.

Rayleigh waves maintain a useful power density at the touch surface dueto the fact that they are bound to the touch surface. A Rayleigh wave isa wave having vertical and transverse wave components with substrateparticles moving along an elliptical path in a vertical plane includingthe axis of wave propagation, and wave energy decreasing with increasingdepth in the substrate. Both shear and pressure/tension stresses areassociated with Rayleigh waves. Mathematically, Rayleigh waves existonly in semi-infinite media. In realizable substrates of finitethickness, the resulting wave may be more precisely termed aquasi-Rayleigh wave. Here, it is understood that Rayleigh waves existonly in theory and therefore a reference thereto indicates aquasi-Rayleigh wave. For engineering purposes, it is sufficient for thesubstrate to be 3 or 4 Rayleigh wavelengths in thickness in order tosupport Rayleigh wave propagation over distances of interest to touchsensor design.

Like Rayleigh waves, Love waves are “surface-bound waves”, i.e. wavesbound or guided by one surface and unaffected by the substrates othersurface provided the substrate is sufficiently thick. In contrast toRayleigh waves, particle motion for Love waves is horizontal, i.e.parallel to touch surface and perpendicular to the direction ofpropagation. Only shear stress is associated with a Love wave.

For purposes of this description, Adler-type acoustic touch sensorsusing Rayleigh-type waves are discussed according to specificembodiments. However, it is recognized that non-Adler-type acoustictouch sensors or acoustic touch sensor using other types of surfaceacoustic waves, including Love waves, may be used in other embodiments.

FIG. 1 is a simplified cross-sectional view of an acoustic touch sensoror touch screen 1. FIGS. 2( a) and 2(b), respectively, are front andback views of substrate 5 of an acoustic touch sensor, according to aspecific embodiment of the invention. In FIG. 2( a), which is a planview of front surface 10 of an acoustic touch sensor, transducers 35 areshown in dotted line to provide a frame of reference in relation to FIG.2( b), which is a plan view of back surface 15 of the acoustic touchsensor where transducers 35 are shown in solid line. To provide afurther frame of reference, X-Y coordinate axes are shown in FIGS. 2( a)and 2(b).

As seen in FIG. 1, touch sensor 1 includes a substrate 5 with a frontsurface 10, a back surface 15, and a curved connecting surface 20joining the peripheral region 14 of front surface 10 and back surface15. Curved connecting surface 20 is described further below inconnection with FIGS. 3( a)-3(f). Front surface 10 has a nominal touchregion 13 on which an object 30 creates a contact to provide inputaccording to the graphical user interface shown on a display (not shownin FIG. 1) disposed behind back surface 15. Nominal touch region 13 isdefined herein as the part of front surface 10 which is the innerportion of front surface 10 that is conventionally considered the activetouch region for conventional surface acoustic wave touch sensors thatis typically not covered by a bezel. Nominal touch region 13 is shownwithin dotted lines in FIG. 2( a), and peripheral region 14 is theportion of front surface 10 external to nominal touch region 13. In aconventional surface acoustic wave touch sensor, peripheral region 14 onfront surface 10 is covered by the bezel. Object 30 is seen in FIG. 1 asa finger, but it is recognized that touches sensed by the acoustic wavesmay include a stylus pressing against front surface directly orindirectly through a cover sheet or an anti-reflective coating,according to some specific embodiments. Acoustic transducers 35 andreflective element arrays 40 are provided on back surface 15.

According to a specific embodiment, touch sensor 1 is a rectangularshaped touch screen that is generally placed in front of a displaydevice, which faces back surface 15. The touch screen is typicallyassociated with a control system (not shown) having a number offunctions. First, an electronic signal is generated, which excites thetransducer to generate a surface acoustic wave which subsequently formsthe sets of waves. A transducer then receives the sets of waves, andtransduces them to an electrical signal. The electrical signal isreceived, retaining significant information with a relatively high datarate in a low level control system. In many embodiments, it is notnecessary to capture phase information contained in the receivedsignals. A controller and/or a processor is thus coupled via wires orleads to the various transducers 35 of touch sensor 1 to control thetransmission and reception of the surface acoustic waves and to processthe necessary waveform perturbations in order to detect the touchcoordinates and position information. The controller, as used herein,means electronics typically including a microprocessor with firmware andanalog electronics to generate excitation signals and to receive signalsback from the touch screen. The controller and/or a processor maps thetouch coordinates and position information to the appropriate controlactions of the user interface shown in the display.

The general structure and operation of the invention, according to aspecific embodiment, are described further below in connection withFIGS. 1, 2(a) and 2(b), and other drawings.

According to specific embodiments of the present invention, substratesmay be formed as a flat plate with a rectangular shape or anon-rectangular shape such as a hexagonal plate. In some embodiments,the propagation substrate 5 is composed of a flat panel or alow-curvature panel. Alternatively the substrate may be curved along oneor both axes as a cylindrical, spherical or ellipsoidal surface orsection surface, or may have other configurations. Large solid anglespherical and complete cylindrical substrates are possible, according toother specific embodiments, where front surface 10 and back surface 15of substrate 5 would be curved rather than planar or flat. Otherembodiments may provide substrate 5 having a cut-out in the center (suchas a doughnut or frame-type structure) with curved connecting surfaces20 on the interior and exterior edges. For example, a polygonal touchsensor may be provided with reflective arrays on each side andtransducers at each vertex. This invention is not necessarily limited tostandard rectangular sensor geometry. It is noted that, for the purposesof this application, the substrate need not be a single monolithicstructure, but rather an acoustically coupled set of elements which maybe homogeneous or inhomogeneous (for example, with Love-type waves, acomposite substrate with an inner material and an outer material havingdifferent densities may be used). The acoustic path from the transmittransducer to the receive transducer may optionally pass through regionsof the substrate that were bonded together as part of the fabricationprocess.

Substrate 5 serves as a propagation medium having surfaces on whichsurface acoustic waves can be propagated. Although the species of thepropagation medium is not particularly limited, a panel in which surfaceacoustic waves and particularly, ultrasonic surface acoustic waves canbe propagated is employed. A display area of the panel includes atouchable coordinate input range, and is generally formed into alaterally symmetrical shape as in the above-mentioned embodiment andparticularly, a linearly symmetrical shape (particularly, a rectangularshape). According to specific embodiments, propagation medium substrate5 constructed as a panel generally has transparency in order to make adisplay disposed under the touch panel visible.

A preferred propagation medium is transparent and isotropic. For touchscreen or touch monitor or touch computer-type devices, suitable glassesfor forming the substrate include soda lime glass; boron-containingglass, e.g., borosilicate glass; barium-, strontium-, zirconium- orlead-containing glass; and crown glass, according to variousembodiments. Examples of preferred transparent substrates may be B 270™available from Schott, PD200 glass available from Asahi Glass Co., orany glass having low loss of surface acoustic wave propagation resultingin better signals, according to some embodiments.

For other embodiments of touch sensors which are not used as touchscreens (for example, an electronic whiteboard application or touchpad), other opaque substrate materials having acceptable acoustic lossesmay be employed, including but not limited to aluminum and steel.Advantageously, aluminum and some other metals may be coated with anenamel with a relatively slow acoustic phase propagation velocity, thussupporting a Love wave with high touch sensitivity (relative tohorizontal shear plate-wave modes) on front surface 10. Under certainconditions, suitable substrates 5 may also be formed of alow-acoustic-loss polymer. Suitable substrates may also be formed from alaminate or other substrate having inhomogeneous acoustic properties.The laminate may advantageously support Love wave propagation withacoustic wave energy concentrated on front surface 10, for example, alaminate of borosilicate glass or Schott B270™ and soda lime glass; orenamel on aluminum.

Various types of transducers may be used with the present invention. Atransducer is a physical element or set of elements which convertsenergy from one form to another. This includes converting betweenacoustic wave modes and converting between electrical and acousticenergy. The acoustically emissive or sensitive structure, which formspart of the acoustic transducer, is typically a piezoelectric element,but is not so limited. For example, electro-acoustic transducers,opto-acoustic transducers, magneto-acoustic transducers,acousto-acoustic transducers (converts energy between one acoustic wavemode and another), and thermo-acoustic transducers, among others, areavailable and could be used. Preferably, ultrasonic wedge transducersmay be disposed on back surface 15 for both transmitting and receivingRayleigh waves or Love waves. Piezoelectric transducers, such as combelectrode transducers, formed of a rectangular prismatic piezoelectricceramic having conductors formed on the surface, may be used in someembodiments to acoustically couple to back surface 15 by mounting a flatsurface of the ceramic element or metallic electrode formed on backsurface 15 of substrate 5. Transducers selected should transmit surfaceacoustic waves of sufficient magnitude so that the received waves, andthe perturbations associated with touches on the particular substrate ofparticular dimensions, can be adequately detected and coordinate dataascertained.

Arrays 40 of reflective elements have a regular spacing or a spacingincrement that can diffract or scatter surface acoustic waves. The knownAdler-type touch sensor design employs a reflective array to coherentlyreflect an acoustic wave at a predetermined angle, where the angle ofincidence equals the angle of reflection. The reflecting array elementsare generally formed parallel to each other, and the angle of thereflecting member or each of the reflecting array elements is generallyapproximately 45° to the X-axis or the Y-axis in order to propagatesurface acoustic waves, such as Rayleigh-type waves, in the directionsof the X-axis and the Y-axis. In accordance with the present invention,reflecting arrays 40 on back surface 15 have reflecting elements thatare formed so as to direct the acoustic waves outwardly toward curvedconnecting surface 20 when such waves are sent from transmittingtransducers; and to collect surface acoustic waves coming from curvedconnecting surface 20 toward receiving transducers. As known from U.S.Pat. No. 5,591,945, expressly incorporated herein by reference, thereflective array elements may also be inclined at other angles toproduce non-rectangular wave paths for the touch screen or to effect amode-conversion between the incident wave and the reflected wave, forexample, quasi-Rayleigh to Love waves.

Reflective arrays may be formed in many ways, for example, printing,etching, stamping of a metal substrate, or shaping of the mold for apolymer substrate. The known reflective arrays are generally formed of aglass frit that is silk-screened onto a soda-lime glass sheet or othersubstrate material, formed by a float process, and cured in an oven toform a chevron pattern of raised glass interruptions. Theseinterruptions typically have heights or depths on the order of 1% of theacoustic wavelength, and therefore only partially reflect the acousticenergy. In order to provide equalized acoustic power at the receivingtransducer, the spacing of the reflective elements may be decreased withincreasing distance from the transmitting transducer, or the balance ofacoustic transmissivity and reflectivity of the reflective elements maybe altered, allowing increased reflectivity with increasing distancefrom the transmitting transducer. Because the touch sensor is generallyplaced in front of a display device, and because the reflective array isgenerally optically visible, the reflective arrays have conventionallybeen placed at the periphery of the front surface of the substrate,outside of the nominal touch region, and have been hidden and protectedunder a bezel. However, with the present invention, reflective arrays 40are formed on back surface 15 of substrate 5, and front surface 10 ofsubstrate 5 does not need any protective bezel over its periphery.

Referring to FIGS. 2( a) and 2(b), one specific embodiment of theinvention provides an Adler-type touch screen system which employstransducers 35 to couple piezoelectric elements to the sensing wave inthe substrate. Touch sensor 1 thus provides a coordinate input devicesystem comprising a substrate 5 having a laterally symmetrical displayarea on which surface acoustic waves can be propagated Like a typicalfour transducer Adler-type system, two pairs of transducers 35 areprovided respectively for the X and Y axes, but instead of being onfront surface 10, transducers 35 are on back surface 15 of substrate 5.In particular, a transmitting transducer 35 a is placed in a Y-axistransmitting area and a transmitting transducer 35 b is placed in anX-axis transmitting area, where the transmitting areas are on backsurface 15 of substrate 5. A receiving transducer 35 c, placed in aY-axis receiving area opposite the Y-axis transmitting area on backsurface 15, is for detecting a Y-coordinate of a touch on front surface10. A receiving transducer 35 d, placed in an X-axis receiving areaopposite the X-axis transmitting area on back surface 15, is fordetecting an X-coordinate of the touch on front surface 10. That is,transmitting transducer 35 a and receiving transducer 35 c are used todetect touch positions of the Y-coordinate, and transmitting transducer35 b and receiving transducer 35 d are used to detect touch positions ofthe X-coordinate. Each transducer 35 may either transmit or receive anacoustic wave, symmetrically. The two transducer pairs are disposed atright angles to define a coordinate system.

The touch sensor also includes a pair of Y-axis reflecting arrays 40 aand 40 b and a pair of X-axis reflecting arrays 40 c and 40 d, butinstead of being on front surface 10, reflecting arrays 40 are on backsurface 15 of substrate 5. Generally, surface acoustic waves travel froma transmitting transducer along an axis on which a reflecting array isprovided near a peripheral edge of the panel. Optionally acousticwaveguide effects may be used to reduce the width of the reflectingarray. The elements of the reflective array each couple part of theacoustic waves with a sensing wave traveling across the panel, andtransmit part to an adjacent element in the array, thus coupling adispersed sensing wave from the entire touch sensitive region to anarrow acoustic beam which couples to the transducer. In general, thesystem transmits a short-time ultrasonic wave signal in the form of aburst by transmitting acoustic wave transducers 35 and reflective arrays40 dispersing the transmitted signals outwardly from back surface 15around curved connecting surface 20, across front surface having nominaltouch region 13, around the opposing curved connecting surface 20inwardly to back surface 15, and through reflective arrays 40 toreceiving acoustic wave transducers 35. Reflecting arrays 40 a and 40 cact as acoustic wave dispersers, and reflecting arrays 40 b and 40 d actas acoustic wave collectors. The system controller analyzes the receivedsignal along the time base, to detect indicated coordinates of the touch(which occurs where the travel paths shown in FIG. 2( a) intersect)within nominal touch region 13 on front surface. The specific embodimentof FIGS. 2( a) and 2(b) provides an XY touch sensor using surfaceacoustic waves.

In particular, surface acoustic waves travel from transmittingtransducer 35 a along the negative (−) Y-axis direction on whichreflecting array 40 a is provided near a peripheral edge of back surface15 of substrate 5. As seen by the solid line arrows indicating thesensing wave travel path in FIGS. 2( a) and 2(b), the elements ofreflective array 40 a each couple or reflect part of the acoustic waveswith a sensing wave: traveling from reflective array 40 a outwardlyalong the negative (−) X-axis direction toward and around the proximateconnecting surface 20 of substrate 5, traveling along the positive (+)X-axis direction across front surface, traveling toward and around theopposing curved connecting surface 20 toward in a negative (−) X-axisdirection reflective array 40 b on back surface 15, and traveling alongreflective array 40 b in a positive (+) Y-axis direction to receivingtransducer 35 c. The elements of reflective arrays 40 a and 40 b alsotransmit part of the acoustic waves to an adjacent element of array 40 aand 40 b respectively. Similarly, surface acoustic waves travel fromtransmitting transducer 35 b along the negative (−) X-axis direction onwhich reflecting array 40 c is provided near a peripheral edge of backsurface 15 of substrate 5. As seen by the solid line arrows indicatingthe sensing wave travel path in FIGS. 2( a) and 2(b), the elements ofreflective array 40 c each couple or reflect part of the acoustic waveswith a sensing wave: traveling from reflective array 40 c outwardlyalong the negative (−) Y-axis direction toward and around the proximateconnecting surface 20 of substrate 5, traveling along the positive (+)Y-axis direction across front surface, traveling toward and around theopposing curved connecting surface 20 toward in a negative (−) Y-axisdirection reflective array 40 d on back surface 15, and traveling alongreflective array 40 d in a positive (+) X-axis direction to receivingtransducer 35 c.

The traveling of surface acoustic waves around curved connecting surface20 is described in more detail in connection with FIG. 3( a), FIG. 3( b)and FIG. 3( c), which are cross-sectional partial views of differentlycurved edge connecting surfaces of the substrate of acoustic touchsensors, according to various specific embodiments of the invention.Incorporated by reference, U.S. Pat. No. 6,567,077 describes chamferedor rounded end or corner faces (acoustic wave direction changingportions) of a propagation medium substrate so that the acoustic wavecan turn around and be propagated from the front surface to the rearsurface of the propagation medium, or from the rear surface to the frontsurface of the propagation medium through the chamfered portion. As seenin FIGS. 1 and 2 of U.S. Pat. No. 6,567,077, an acoustic surface wave orthe like traveling on the surface of a spherical propagation mediumcorresponds to the outline of a section made by cutting the sphere alonga plane including the center of the sphere, and such a wave traveling onthe surface of a columnar propagation medium travels spirally on thesurface of the propagation medium. The acoustic wave thus is able tochange directions by traveling across the curved surface of thepropagation medium with negligible loss. FIGS. 3 and 4 of U.S. Pat. No.6,567,077 illustrate rounded peripheral edge portions of the propagationmedium that are chamfered to form a hemispherical-section having aradius R.

FIG. 3( a) illustrates a rounded portion 20 of propagation medium orsubstrate 5 having a radius R that is half the thickness T of substrate5, similar to that hemispherical-section shown in FIG. 4 of U.S. Pat.No. 6,567,077. With a hemispherical-section having radius R, the lengthb of the rounded portion of propagation medium equals R, which equalsT/2 when T is assumed to be five Rayleigh-wave wavelengths λ. However,the present inventors have determined that a hemispherical-section isnot necessary to achieve the ability to change directions of the surfaceacoustic wave traveling across the curved surface of propagation mediumwithout appreciable loss. As seen in FIG. 3( b), rounding the top andbottom sharp edges of substrate 5, such that the respective radius R ofcurved surface 20 is about T/4 results, in surface 20 of substrate 5having a length b that is significantly less than the length b for ahemispherical-section. Moreover, as seen in FIG. 3( c), even modifyingthe top and bottom sharp edges of substrate 5 such that the respectiveradius R of curved surface 20 is about T/8 results in surface 20 ofsubstrate 5 having a length b that is even smaller than that of FIGS. 3(a) and 3(b).

The present inventors have shown that as R (or b) increasinglyapproaches T/2 (or 5λ/2 for T=5λ), the curved surface 20 is somewhatbetter for surface acoustic wave transmission; but as R (or b)decreasingly approaches T/8 and remains much greater than the wavelengthof the surface acoustic wave, the touch sensor's border region desirablybecomes smaller. Accordingly, a tradeoff of these desires as well asconsideration of cost factors is made, and for a specific preferredembodiment, R has been selected to be about T/4 to about T/8. It isrecognized that radii R can be less than T/8 as long as there is asufficient received signal and other design constraints are met. Asaluminum is similar to glass as a substrate for surface acoustic wavepropagation, experimental measurements were performed by the inventorson an aluminum substrate having curved connecting surface 20 withdifferent radii of edge curvature and thickness (T) of about 3 mm. Theexperiment used acoustic wedge transducers having an approximately 3 mmwide ceramic piezoelectric element (in the family of PZT relatedpiezoelectric ceramics, and having a fundamental resonance nominally at5.53 MHz). The transmitting transducer was excited to transmit a surfaceacoustic wave that traveled across the substrate's front surface, towardand around the substrate's curved connecting surface having radius orradii R, and then traveled across the substrate's back surface formeasurement by receiving transducer. For a given excitation voltage atfrequency 5.53 MHz applied to the transmitting transducer, the amplitudeof the signal measured over the relevant delay time for the receivedsignal at the receiving transducer did not appreciably change fordifferent radii, as seen in FIGS. 3( e) (where the radii R=T/4) and FIG.3( f) (where the radii R=T/8) compared to FIG. 3( d) (where the radiusR=T/2). These measurements show the amplitudes of the received signalsmeasured at the expected delay time (the expected received signalarriving with a delay time of between about 17 and about 25microseconds) do not appreciably change for a given excitation. Theother waveforms on either side of the received signals are merelyartifacts based on other unintended and extraneous wave or modepropagations in the substrate that occurred in the test system.

For curved connecting surface 20 of R having a range of about T/4 toabout T/8, the inventors' experiments on aluminum propagation materialssuggest that the smaller R is acceptable for surface acoustic wavetransmission on glass propagation substrates but only if there are no“kinks” or sharply beveled edges. For glass vendors, a “rounded edge”glass substrate typically still has kinks. As described in connectionwith the formula shown in FIG. 9 of U.S. Pat. No. 5,739,479, bevel angleθ of 16 degrees between the bevel surface and the active touch surfacefor a monolithic soda lime glass substrate results in significantly lessthan a 6 dB signal loss over the acoustic path. A bevel angle θ of 25degrees between the bevel surface and the active touch surface for amonolithic soda lime glass substrate showed about 8 dB measured signalloss over the acoustic path. Quadratic extrapolation from 25 degreesbevel data implies a 14 dB signal loss for a bevel angle θ of 33degrees. In the specific embodiments, any kinks should have a bevelangle θ of less than about 10 degrees to have a loss of less than 3 dBwith four kinks (two for each curved portion 20 on opposite sides ofsubstrate 5) in a completed acoustic path.

The rounding of sharp bevel edges of a glass substrate can be achievedby grinding the glass to the desired profile and then optionallypolishing to obtain the desired smooth profile for a specificembodiment. Kinks including for example a step 16 such as shown in FIG.3( g) may be minimized or avoided, according to some embodiments. Suchkinks or steps might result when a grinding tool 17 (whose cross sectionis shown) having the desired radius or radii R is used and the substrate5 has an offset in alignment with the tool 17 and/or there arevariations in the thickness of different substrates 5. Such kinks orsharply beveled edges on the edge of the touch substrate that mayundesirably result in acoustic parasitic signals may be minimized oravoided, according to some embodiments. Parasitic signals (such as mayresult from conversions between surface acoustic waves and plate wavesor other wave modes) undesirably may result in the touch sensorappearing to detect “ghost” touches, which are not actual touches, ormeasuring distorted coordinates, and such parasitics should beminimized, according to such specific embodiments. In FIG. 3( g),grinding tool 17 provided with, for example, R=T/3 is used with aconventional computer numerically controlled (“CNC”) grinding machine.Step 16 results in undesired parasitic signals (from plate waves), evenwhen the step (created by the offset or substrate thickness variation)is on the order of about the surface acoustic wave wavelength. In orderto provide better tolerances for such variations in substrate thicknessand/or an offset between the substrate and the grinding tool used,improved grinding tool 18 which has, for example, R=T/6 and a widermouth with a taper angle α, ranging between about 10 to 12 degrees forsome embodiments, and R=T/3 with a taper angle of about 3 to 5 degreesin other specific embodiment, may be used, as seen in FIG. 3( h). FIG.3( h) shows the curved edge profile of substrate 5 manufactured usingtool 18 when substrate 5 is not offset from, but in desired alignmentwith, the tool; FIG. 3( i) shows the curved edge profile of substrate 5manufacturing using tool 18 having R=T/6 when substrate 5 is offset fromthe tool 18; and FIG. 3( j) shows the curved edge profile of substrate 5manufactured using a grinding tool 17′ (similar to tool 17 shown in FIG.3( g) but with, for example, R=T/3, the tapered opening having angle α)when substrate 5 is offset from tool 17′. Although for a specificembodiment where the frequency is about 5.53 MHz, the use of a grindingtool having 4 degree taper angle and R=T/3 for a substrate thickness ofabout 3 mm was most desirable (but grinding tool with a 12 degree taperangle and R=T/6 for the same substrate thickness had undesirableparasitics), many factors affect both the strength and acceptable levelof parasitic signals so that for some applications it may be acceptableto use a grinding tool of 12 degree taper angle and R=T/6. Depending onthe alignment achieved or existing tolerances, the front and backsurfaces 10 and 15 of substrate 5 are coupled via at least one curvedconnecting surface that may include flat portion(s), such as between thefront surface 10 and a curved portion (the angle being less than 5degrees between the flat portion and front surface 10 according tospecific embodiments), between two respective curved sections, and/orbetween back surface 15 and a curved section (the angle being less than5 degrees between the flat portion and front surface 10, according tospecific embodiments). Of course, the examples shown could be similar towhen the same substrate with a specified substrate thickness has somemanufacturing thickness variation. The edges, as mentioned above, may beoptionally polished for smoothness. Other methods of rounding the sharpedges of substrates may include plastic molding, glass molding oraluminum molding, according to other embodiments.

It should be recognized that curved connecting surface 20 may be ofvarious cross-sectional profiles, such as shown in FIGS. 3( a)-3(c) orFIGS. 3( h)-3(j), and that curved connecting surface 20 includes atleast one curved section of a radius R. FIGS. 3( b)-3(c) illustrateexamples of curved connecting surface 20 having two symmetrically curvedsections (each having the same radius R) coupled by a straight section,but with other embodiments of the invention curved connecting surface 20may have two asymmetrically curved sections (having different values ofR) coupled by a straight section. FIGS. 3( h)-(j) are cross-sectionalpartial views of differently configured curved connecting surfaces ofthe substrate of acoustic touch sensors, according to further specificembodiments, as discussed above. Of course, views in FIGS. 3( a)-3(c)and 3(h)-13(j) are not intended to be exhaustive but provide examples ofthe substrate curved edge profile. Furthermore, the radius R in FIGS. 3(g), 3(h), etc. can be generalized from the radius of an arc of a circleto the minimum radius of circles tangent to a curve of continuouslychanging curvature. Above it has been assumed that touch sensorsubstrate thickness T is about five Rayleigh-wave wavelengths λ as isoften typical in most commercial product designs so that expressionssuch as R=T/3 can be re-expressed as R=5λ/3. Similarly, the expressionR=T/6 can be re-expressed as R=5λ/6. Of course, the expressions would bemodified for substrate thickness T that is different than fiveRayleigh-wave wavelengths. For example, good parasitic suppressionbenefits have been observed for edge rounding radius of R=T/2 for 5.4λthick glass. For, 5.4λ thick glass this edge rounding radius can also beexpressed as R=2.7λ. While not required for acoustic reasons, there ismarket interest in SAW touchscreens built from much thicker (andtempered) glass substrates such as the SecureTouch™ products of TycoElectronics with approximately 11λ thick glass; bezel-less variants ofsuch products could be made with rounded edges of radius R=2.7λ for goodparasitic wave suppression.

FIG. 4 is a simplified cross-sectional view of an acoustic touch sensordevice 50 (also referred to as touch device 50), which may be a touchmonitor, a touch computer, touch video display or signage, or touchmobile device, according to various specific embodiments of theinvention. Similar to the touch sensor 1 of FIG. 1, touch device 50includes substrate 5 with front surface, back surface 15, and curvedsurface 20 joining the peripheral region 14 of front surface and backsurface 15. Front surface 10 has a nominal touch region 13, the innerportion of front surface, on which an object 30 makes contact to provideinput according to the graphical user interface shown on a display 25(shown in FIG. 4) coupled to back surface 15. According to a specificembodiment, display 25 may be optically bonded to back surface 15, butin other embodiments display 25 does not contact back surface 15 but ismerely disposed under substrate 5 and held stable with respect tosubstrate 5 by housing 55 and an adhesive. FIG. 4 also illustrateselectronics including touch controller (as described in detail below) asbox 69 with leads connecting to wires and/or cables (not shown). Nominaltouch region 13 is defined as the portion of front surface 10 withindotted lines in FIG. 2( a), and peripheral region 14 is the portion offront surface 10 external to nominal touch region 13. Object 30 is seenin FIG. 4 as a finger, but it is recognized that touches sensed by theacoustic waves may include a stylus pressing against front surfacedirectly or indirectly through a cover sheet (provided the cover sheetcovered those surfaces of substrate 5 that are used for acoustic sensingwave travel paths) or an anti-reflective coating, according to somespecific embodiments.

The general structure and operation of the touch aspects of theinvention, according to a specific embodiment, are similar to thosedescribed above in connection with FIGS. 1, 2(a) and 2(b), with somedifferences that are now described.

Acoustic transducers 35 and reflective element arrays 40 are coupled viaan acoustically benign layer 60 to back surface 15, according to thisspecific embodiment. For purposes of this description, an “acousticallybenign” material is one that propagates surface acoustic waves withoutrapid attenuation, preferably resulting in only small changes to thesurface acoustic wave's velocity for easier manufacturing control of thewave's velocity despite factional changes in material thickness.According to some specific embodiments, acoustically benign layer 60 ispreferably opaque and is able to both bond with substrate 5 and serve asan adequate processing surface for transducers 35 and reflective arrays40 formed thereon. For example, wedge transducers 35 are bonded on, andreflective arrays 40 are formed with frits on, layer 60. In someembodiments, layer 60 may be a thin film of black inorganic material(such as an ink or a paint that is screen printed, painted or sputteredor otherwise applied) on back surface 15 of substrate 5.

According to a specific embodiment, acoustically benign layer 60 may bean inorganic black paint made of ceramic resin or porcelain enamel typesof material. Examples of layer 60 may include titanium dioxide (TiO₂) orsilica (SiO₂) that can be combined in some embodiments with cobalt (Co),chromium (Cr), copper (Cu), nickel (Ni) or manganese (Mn) for richcolors. Certain high heat resistant paint formulas, such as RustOleum™high heat ultrapaint or Ferro™ glass coating 1597 may be suitable foruse as acoustically benign layer 60. In other embodiments, layer 60 maybe white or other colors. Layer 60 can provide an appealing or vibrantvisual appearance, while hiding transducers 35 and arrays 40 from viewthrough substrate 5. Layer 60 may also have a composite of colors usedin patterns, other decorative features, and/or useful features such asto indicate edge sensitive touch function inputs according to specificembodiments of the invention. In some embodiments, acoustically benignlayer 60 may be translucent, so that light sources (such as lightemitting diodes) may be disposed behind back surface 15 to shine throughtranslucent layer 60 when activated. Of course in some embodiments,concealing transducers 35 and arrays 40 may not be desired if a moreindustrial or technical appearance is sought, in which case layer 60 maybe transparent, not used at all (such as shown in FIG. 1), or only usedon a portion of peripheral region 14 of back surface 15.

When disposed between back surface 15 and transducers 35 and arrays 40,layer 60 is thus visible through substrate 5 (and with embodiments wherelayer 60 is opaque, shielding from view transducers 35 and arrays 40)and so appears to users to frame nominal touch region 13 (which is shownwithin dotted lines in FIG. 5, which is a simplified explodedperspective view of acoustic touch sensor 50), according to a specificembodiment of the invention. According to a specific embodiment, touchsensor 50 is a rectangular shaped touch device that integrates display25, which faces back surface 15, such that the display is visiblethrough substrate 5. In some embodiments, a thin layer 60 could even beapplied to peripheral portion 14 of front surface 10 of substrate 5.

The thickness of layer 60 should be controlled so that the signalattenuation resulting from layer 60 is balanced with any cosmeticobjectives relating to its opacity. As seen in FIG. 13, the wavevelocity (or more precisely the phase velocity of wave fronts incontrast to the group velocity of wave packets) of surface acousticwaves propagating in the region of layer 60 for a touch sensor isaffected by the coating thickness of layer 60. For many materials thatcan be sintered at temperatures compatible with glass substrates, thespeed of sound is slower than for glass. In this case, the wave velocityv_(SAW) is reduced as the portion of the surface acoustic wave powerpropagating through the layer 60 increases (i.e., the thickness of layer60 results in slower wave propagation). If the material of layer 60 hasa faster speed of propagation of sound than the material of substrate 5,then the wave velocity v_(SAW) is increased as the portion of thesurface acoustic wave power propagating through the layer 60 increases(i.e., the thickness of layer 60 results in faster wave propagation).From the perspective of manufacturing process control of the wavevelocity v_(SAW), the ideal material for layer 60 would result in nochange in wave velocity and hence no variation in wave velocity with thethickness of layer 60. For the layer 60 material used to generate thedata for FIG. 13, it was also observed that very strong attenuationoccurs when the layer 60 thickness is over 50 microns for thesefrequencies. For a specific embodiment where the frequency is about 5.53MHz and the substrate is a B270 glass, a thickness of layer 60 rangingbetween about 15-21 microns, or preferably 12-20 microns, was found tobe an acceptable thickness that balanced the desire for low waveattenuation and clean cosmetic appearances (high opacity withoutperceived translucence) when using Ferro black ink 24-8328 for layer 60.Other ink products may exist that have higher optical densities enablinga clean cosmetic appearance with thinner coatings, which could bedesirable for acoustic design reasons as it may reduce acousticattenuation and reduce variations in wave velocity.

Touch device 50 includes a housing 55 which contains and protectsdisplay 25, layer 60, transducers 35, reflective element arrays 40, aswell as other components of the device, such as processors, controllers,connectors, and other passive or active electronics or parts that may beneeded for operation of the device. For simplicity, these othercomponents are not shown.

The touch sensor systems or devices according to the present inventiontypically employ an electronic control system (not shown in thedrawings), which generates the acoustic waves and determinesperturbations indicative of a touch position or coordinate. Theelectronic control, in turn, interfaces with a computer system (notshown in the drawings), for example a personal computer, embeddedsystem, kiosk or user terminal as a human interface device. The computersystem may therefore be of any suitable type, and for example mayinclude display 25, audio input and/or output capability, keyboard,electronic camera, other pointing input device, or the like. Thecomputer system operates using custom software, but more typically usinga standard operating system such as Microsoft Windows (e.g., 3.1, 3.11,7, WFW, CE, NT, 95, 98, etc., or other operating system which conformsto a set, subset or superset of Windows Application Program Interfacesor APIs), Macintosh operating system, UNIX variants, or the like. Thetouch sensor may thus be employed as a primary or secondary pointingdevice for a graphic user interface system to receive user input. Thetouch sensor controller and computer system may also be integrated, forexample in an embedded system.

According to the specific embodiment, housing 55 is coupled to substrate5 and may be environmentally sealed at the periphery 65 by some suitablemeans such as a strip of closed cell foam, a soft rubber gasket with awiper blade cross section, and narrow adhesive bond of RTV silicone oran epoxy, or other material and contact width that is acousticallybenign. Thus, the seal at periphery 65 is provided to allow sufficientacoustic wave energy to permit touch sensor operation, while protectingarrays 40 and transducer 35, as well as display 25 and othercomponents/wires/parts within housing 55 from contamination. In someembodiments, in addition to the seal at periphery 65, substrate 5 mayhave posts (not shown) connected at certain locations, such as near itscorners on back surface 15, to attach to housing 55. In some otherembodiments, such as described below for FIGS. 6( a) and 6(b) and 6(c),substrate 5 may be joined and/or bonded to housing 55 via other hardwaresuch as a sub-bezel.

According to a specific embodiment, substrate 5 may be a sheet of about3 mm thick annealed glass, a heat tempered or chemically strengthenedglass. The nominal touch region 13 is located within front surface 10 ofsubstrate 5. There is no interruption of the flat front substratesurface 10, according to the specific embodiment, and no bezel thereonis used or desired. In particular, it is noted that there are noreflective arrays or transducer components on front surface 10 ofsubstrate 5.

Behind the nominal touch region 13 of substrate 5, display 25 isoptically bonded in a bonding region with a suitable bonding material toback surface 15 of substrate 5, according to a specific embodiment. Theoptical bonding material is an acoustically absorbing, opticallytransparent bonding material such as 3M™ Optical Clear Adhesive 8171.Optical bonding material is a solid material in intimate mechanicalcontact with substrate 5 and therefore acoustically absorbs anyunintended plate wave and/or surface acoustic wave paths on back surface15 that would otherwise propagate between opposing pairs of reflectivearrays 40. Display 25 may be, for example, a liquid crystal display(LCD), organic light emitting device (OLED) display, electrophoreticdisplay (EPD), vacuum fluorescent, cathode ray tube, or other display.Alternately, display 25 may be a reverse projection screen that isoptically bonded to substrate 5. In some embodiments, display 25 isoptionally coupled to mechanical supports 67 for attachment to housing55. In other embodiments, display 25 may not be optically bonded tosubstrate 5, but instead uses mechanical supports 67. In still furtherembodiments, such as described below for FIGS. 6( a)-6(c), display 25may be joined and/or bonded to housing 55 via other hardware such as asub-bezel or such as described for FIGS. 6( d)-6(h). For embodimentswhere optical bonding material is not used, it may still be desirable toapply an optically transparent and acoustically absorbing material, suchas by adhering an anti-spall material or by applying a thin transparentpolymer layer by screen printing, behind the nominal touch region 13 onthe back surface 15 of substrate 5 so that parasitic signals caused byunintended plate wave or surface acoustic wave paths between opposingpairs of reflective arrays 40 are minimized or avoided.

On back surface 15 of substrate 5, four reflective element arrays 40 andfour Rayleigh-wave wedge transducers 35 are provided in an arrangementsimilar to, e.g., the system shown in FIGS. 2( a) and 2(b). Note thatany unintended acoustic paths on back surface 15 between the reflectivearray 40 pairs are blocked by the acoustically absorbing optical bondingmaterial of display 25, in embodiments where display 25 is opticallybonded to substrate back surface 15.

According to a specific embodiment, FIG. 6( a) illustrates across-sectional partial view of a corner configuration and mountingscheme for a bezel-less acoustic touch sensor device, and FIG. 6( b) isa partial plan view of a corner configuration and mounting scheme forbezel-less acoustic touch sensor device, according to a specificembodiment of the invention. As seen in FIGS. 6( a) and 6(b), housing 55including a sub-bezel or flange 110 disposed beneath substrate 5encloses the various components of touch sensor device 50. From theunmagnified perspective of a user of the device, the entire top surface117 of the outer portion of flange 110 may appear to be contacting backsurface 15 of substrate 5. However, top surface 117 of the outer portionof flange 110 actually is separated from surface 15 has an air gaptherebetween, except for certain locations where protrusions 119 areformed on surface 117 of flange 110. Protrusions 119 act as spacersbetween back surface 15 of substrate 5 and flange 110. According to aspecific embodiment, protrusions are on the order of 10 microns high andmake limited physical contact with back surface 15 of substrate 5 onlyat certain locations, and those contact areas are not sufficient toresult in any appreciable surface acoustic wave absorption that mightotherwise be caused if surface 117 of flange 110 was actually in contactwith back surface 15. In some embodiments, the air gap between surface15 and top surface 117 may have disposed therein an acoustically benignperimeter sealant such as a strip of closed cell foam or rubber gasketwith a wiper blade cross section in order to prevent contaminants orliquids from entering housing 55 and potentially damaging display 25 orthe electronic components therein.

Providing a cross-sectional view taken across line A-A′ shown in FIG. 6(b), FIG. 6( a) illustrates a peripheral display bonding layer 115 thatsecures display 25 to flange 110 of housing 55, and a peripheralsubstrate bonding layer 120 that secures touch substrate 5 to flange 110of housing 55. Flange 110 of housing 55 has a cut-out to accommodate thedimensions of transducer 35, which is coupled to back surface 15 eithervia acoustically benign layer 60 (not shown) or directly, according tospecific embodiments. Peripheral display bonding layer 115 may be adouble-sided adhesive tape, an epoxy, or any other means to provide areliable mechanical bond, and peripheral substrate bonding layer 120 maybe an epoxy, double-sided adhesive tape, or any other means to provide areliable mechanical bond. It is desirable that the material of bondinglayer 120 is acoustically absorptive and as typically the case formechanically or structurally reliable adhesive. In a specificembodiment, four millimeter wide double-sided adhesive tape may besufficient to be used as bonding layers 115 and/or 120. Two reflectivearrays 40 are shown in dotted line in FIG. 6( b) to illustrate theirplacement with respect to transducer 35, according to a specificembodiment. With this mounting configuration, arrays 40 do not makecontact with flange 110 due to protrusions 119. Note that any unintendedacoustic paths that would otherwise travel on back surface 15 betweenopposing pairs of reflective arrays 40 are blocked by the peripheralsubstrate bonding layer 120 in this embodiment.

FIG. 6( c) illustrates a cross-sectional partial view of another cornerconfiguration and mounting scheme for a bezel-less acoustic touchsensor, according to another specific embodiment. FIG. 6( c) does notshow a cross-section along line A-A′ of FIG. 6( b), but shows across-section in a similar area in accordance with this specificembodiment where transducer 35 is disposed behind substrate 5 in acorner location higher than shown in the embodiment of FIG. 6( b).Similar to the embodiment shown in FIG. 6( a), housing 55 including asub-bezel or flange 110 disposed beneath substrate 5 encloses thevarious components of touch sensor device 50. In this embodiment,acoustically benign layer 60 is shown disposed between back surface 15of substrate 5 and transducer 35 and reflective array 40. Anacoustically benign perimeter sealant 121 is disposed between layer 60and flange 110 to provide a barrier for contaminants or liquids fromentering housing 55 and potentially damaging display 25 or theelectronic components therein. For a specific embodiment, sealant 121may be a strip of closed cell foam (such as Volara™ foam) or rubbergasket with a wiper blade cross section. Display 25 has a bracket 123disposed thereon via bonding layer 115 described above. Bracket 123 iscoupled to substrate 5 via acoustically benign layer 60 by bonding layer120. Bracket 123, which optionally may be coupled to housing 55 toprovide additional secure mounting of substrate 5, serves to physically(and/or electrically and/or acoustically) isolate any cable(s) orwire(s) 124 (indicated by dotted line circle) for the touch sensorand/or display 25 from reflective arrays 40. Bracket 123 may be aframe-like structure, constructed of a metal material, having cut-outs(not shown) so that, for example, a wedge transducer 35 and itsassociated wiring may be provided through the cut-out and tucked underbracket 123. In this embodiment, bracket 123 may be in contact withreflective arrays 40, but the metal material has a surface that does notmake sufficient contact to acoustically attenuate or otherwise interferewith the traveling surface acoustic waves. This mounting configurationincluding bracket 123 enables satisfactory bonding to display 25 havinga narrow perimeter border and the necessary isolation of cables and/orwiring 124 to integrate substrate 5, transducers 35, arrays 40 anddisplay 25 within housing 55.

FIG. 6( d) is a front view of a bezel-less acoustic touch sensorprovided as part of another system such as a kiosk system, according tosome specific embodiments. For example, the bezel-less acoustic touchsensor 1 may be desired to be part of a larger system, such as for kioskthat has a frame 57 surrounding the acoustic touch sensor. Of course, ifthe sensor 1 is rear mounted as part of a countertop, frame 57 couldextend beyond the perimeter shown in FIG. 6( d). FIGS. 6( e)-6(h) showcross-sectional perspective slices looking into arrows B-B′ shown inFIG. 6( d), and the reflective arrays and transducers of sensor 1 arenot shown in these views.

FIG. 6( e) illustrates a partial cross-sectional slice perspective viewof a sealing scheme for a bezel-less acoustic touch sensor shown justprior to flush mounting as part of a larger system such as a kiosksystem, according to a specific embodiment. FIG. 6( f) illustrates apartial cross-sectional slice perspective views of a mounting scheme fora bezel-less acoustic touch sensor shown mounted as part of anothersystem such as a kiosk system, according to the embodiment of FIG. 6(f). To provide context for the sealing scheme of touch sensor 1 withframe 57 of the larger system, FIGS. 6( e)-6(f) show a portion of touchsubstrate 5 having front surface 10 and back surface 15 havingacoustically benign layer 60 coated thereon in the peripheral region 14,with display 25 coupled to back surface 15 such that the images on thedisplay are visible through substrate 5 in the region 13. Made ofelastomer material or other acoustically benign material, a gasket 61surrounds, and is in contact with, the curved connecting surface 20along the periphery of substrate 5. Gasket 61 may be an extruded,determinable silicon or stiff rubber, according to specific embodiments.Prior to mounting, gasket 61 has a wiper blade shaped cross-sectionalprofile, with a protruding head that is in contact on the top half ofthe curved connecting surface 20 of substrate 5 and then extends outwardin a blade or flange, and with a downward stem portion. As seen in FIGS.6( e) and 6(f), a bracket 63 is disposed between the right side of thestem portion of gasket 61 and a bottom half portion of the curvedconnecting surface 20 at peripheral portion of the layer 60-coatedbottom surface 15 of substrate 5. Formed as a frame around the peripheryof substrate 5, bracket 63 may be made of metal or plastic and is usedto control the compression of gasket 61 against substrate 5. Bracket 63has double sided adhesive (not shown) applied to fasten to the backsurface 15 of substrate 5. This adhesive is interior (toward the display25) to the transducers and reflective arrays on back surface 15. Abracket 71 made of spring steel or other spring metal material, alsoreferred to as a spring bracket, is disposed between the left side andbottom of the stem portion of gasket 61 and at least part of bracket 63.Bracket 71 positions gasket 61 against the substrate 5 so that constant,even pressure is applied. In combination, gasket 61, bracket 71 andbracket 63 provide a consistent yet minimal contact to substrate 5, withan even pressure to provide good sealing from moisture and theenvironment while minimizing the contact area of gasket with substrate 5to avoid excessive acoustic attenuation of the acoustic wavespropagating around curved connecting surfaces 20. Bracket 73 is attachedat least to frame bracket 63 via double sided adhesive 81. Although onlypartially shown in the figures, it should be recognized that adhesive 81may also be disposed between the bottom surface of spring bracket 71 andbracket 73. Bracket 77, which is conventionally connected to frame 57and is height adjustable via a slot through which a conventionalfastener 79, such as a screw with nut (not shown), is disposed toconnect with bracket 73 which has a hole or slot that overlaps with thatof bracket 77. Each of bracket 73 and 77 may be formed as a framegenerally proportional with the periphery of sensor 1 and/or multiple ofthese brackets may be used in various locations along the periphery.Bracket 73 and 77 may be made of metal.

FIG. 6( g) and FIG. 6( h) illustrate partial cross-sectional sliceperspective views of two other sealing schemes for a bezel-less acoustictouch device shown mounted as part of another system such as a kiosksystem, according to other specific embodiments. The description ofelements shown in FIGS. 6( g)-6(h) that are the same as shown in FIGS.6( e)-6(f) is not repeated here. The embodiment of FIG. 6( g) is similarto the embodiment shown in FIG. 6( e)-6(f), except that the frame 57′has a thickness that is thin enough so that it may rest on the top wiperblade portion of gasket 61, exposing only a minimal amount, such asabout 1 mm width, of gasket 61 between substrate 5 and frame 57′.Brackets 77 and 73 may be coupled together via an appropriatelydimensioned spacer 83 (if needed) with fastener 79, so as to provideadequate mounting of the touch sensor 1 to the frame 57′. The embodimentof FIG. 6( h) is also similar to the embodiment of FIGS. 6( e)-6(f), asframe 57″ may be of variable thickness, except that this embodiment issuitable even when the edges of frame 57″ may be rough rather thansmooth finished edges. In the embodiment of FIG. 6( h), the wiper bladeportion of gasket 61 may be disposed on top of the frame 57″ to coverits rough edges and provide good sealing as well as the other advantagesdiscussed for the other embodiments.

The specific embodiment of FIGS. 2( a) and 2(b), described above,provides an XY surface acoustic wave touch sensor capable of detectingtouches on nominal touch region 13, as well as on peripheral region 14external to nominal touch region 13 on front surface 10 and/or toucheson the curved connecting surface 20. However, when a touch is made onperipheral region 14 or on curved connecting surface 20, the XY touchsensor according to this specific embodiment can detect only onecoordinate of position: either an X-coordinate or a Y-coordinate. Ifonly the X-coordinate is detected from a touch to the top or bottom edgeconnecting surface 20 or the top or bottom portion of peripheral region14, or if only the Y-coordinate is detected from a touch on either sideedge connecting surface 20 or either side portion of peripheral region14, there is a need for another coordinate or position data to resolvethe ambiguity of which area (top, bottom, right or left) was touched.When edge sensitive touch functions are provided according to thepresent invention, this resolution can be done in various mannersaccording to different embodiments described below. For purposes of thedescription herein, “edge sensitive touch functions” are intended tomean interactive touch functions based on detecting touches made to theperipheral region 14 and/or to curved connecting surface 20.

FIG. 7 is a perspective view of a bezel-less acoustic touch sensordevice 50, such as a touch monitor, with edge sensitive touch functionsas seen in a magnified bottom right corner view, according to specificembodiments of the invention. FIG. 7 includes the various elementsalready discussed in connection with touch sensor 1 of FIG. 1 and touchsensor 50 of FIG. 4, and those elements will not be described againhere. Of course, it should be recognized that if the acoustic touchsensor is not integrated into a monitor but is instead integrated into acomputer or a portable touch device, monitor stand 90 is not needed. Asseen in FIG. 7, which provides a magnified corner view of touch sensordevice 50, front surface and curved connecting surfaces 20 a and 20 b ofsubstrate 5 are shown coupled to housing 55. Front surface includesperipheral region 14 (shown external to dotted lines defining a nominaltouch region 13 (within dotted lines), which is disposed over display25.

Certain edge sensitive touch functions may be detected by determining atouch on the appropriate part of peripheral region 14 or on curvedconnecting surface 20. Other edge sensitive touch functions may bedetected by determining a gesture is occurring. With a gesture, when aninitial touch on a part of peripheral region 14 or on curved connectingsurface 20 is recognized, it is then observed if the perturbation in thereceived surface acoustic wave signal has a time delay that isincreasing with sequential scans or decreasing with sequential scans asa signature that touch is a gesture, such as a sliding or swipingmotion. With a gesture, the absolute coordinates of the position of thecontinuous touches may not matter, as long as the increase or decreasewith time occurs after an initial touch is detected in the appropriateedge sensitive touch function region.

According to a specific embodiment, peripheral region 14 may havedifferent icons or printed buttons, such as in this example shown box95, box 97, icon 101 and/or icon 103, that are provided as part of layer60 (which could be disposed on back surface 15 or front surface ofsubstrate 5, according to various embodiments). Since acousticallybenign layer 60 may be opaque and use a combination of colors includingblack, white and/or other colors, the particular icons or boxesdesignating buttons or other edge touch sensitive functions on theperipheral region 14 may be customized. Therefore, a touch detected onthe appropriate part of peripheral region 14 would result in thedesignated function action, as mapped by the system control softwareand/or firmware. Alternately or in addition, touches detected on curvedconnecting surfaces 20 a and/or 20 b could be used to result in thedesignated function action. Where the edge touch detection capability ofconnecting surface 20 is used, surface 20 itself may have a thin layerof material (similar to layer 60) thereon to designate the appropriateedge sensitive touch function, or housing 55 proximate to the relevantportion of connecting surface 20 may have printed icons such asincreasing arrow 105 or decreasing arrow 107 to indicate a desiredincreasing or decreasing, respectively, of the device volume, displaybrightness, display contrast, or other designated or configurable edgesensitive function. The portion of surface 20 proximate to arrows 105and 107 may be touched in a sliding motion to provide a sliding controlof an aspect of the device.

Buttons 95 and 97 may be assigned predetermined functions (such ason/off, or awake from sleep mode, or other operation) or such functionsmay be configurable by a user or manufacturer of the device 50 usingconfiguration software to map the particular touch region to aparticular function. As a further example, the icon 101 (indicated as asun for display brightness adjustment) on peripheral region 14 may betouched to indicate to the device controller that the proximate part ofcurved connecting surface 20 may be slidably touched to increase ordecrease the display brightness. As a still further example, the icon103 (indicated as a half darkened circle for display contrastadjustment) on peripheral region 14 may be touched to indicate to thedevice controller that the proximate part of curved connecting surface20 may be slidably touched to increase or decrease the display contrast.It is clear that a microphone icon could be similarly provided to enablevolume control. Alternatively, the arrows 105 and 107 could beconfigured to cause two-finger touches as zooming in or out of an imageon display 25, or scrolling of images on display 25, etc.

Although various icons and buttons are shown in one corner of device 50in the example shown in FIG. 7, it is recognized that one, all, or acombination of the icons or buttons may be used for edge sensitive touchfunctions. For instance, for some embodiments, there is not necessarilyany need to have both increasing arrow 105 and decreasing arrow 107, butone might suffice. Further, many different edge sensitive touchfunctions than those described above could be enabled by the edgesensitive touch function features of the present invention, according tovarious embodiments. It should be recognized that although FIG. 7illustrates 20 b and region 14 b as being on the right side of device 50(as FIG. 7 serves to provide mere examples of the types of edgesensitive touch functions), surface 20 b and region 14 b shown in FIGS.11( a)-11(d) are on the left side of device 50. However, surface 20 band region 14 b of FIG. 7 may be situated on the right or left side ofdevice 50, depending on the specific embodiment. That is, the locationof the edge sensitive touch functions can be available on peripheralregion 14 and/or surface 20 any of the top, bottom, right side or leftside, or any combination thereof, by using different specificembodiments according to the invention.

Various other specific embodiments are now described that have similaroperation as described above in connection with FIGS. 2( a) and 2(b) fordetecting the X-Y coordinates for a touch on nominal touch region 13,and that description is not repeated here. The aspects of theseembodiments that are to be described focus on providing anothercoordinate or additional position data to resolve the ambiguity of thearea touched (top, bottom, left or right) when edge sensitive touchfunctions are provided according to the present invention.

FIG. 8( a) and FIG. 8( b), respectively, are front and back views ofsubstrate 5 of an acoustic touch sensor, according to a specificembodiment of the invention. FIG. 9( a) and FIG. 9( b), respectively,are front and back views of substrate 5 of another acoustic touchsensor, according to another specific embodiment. FIG. 10( a) and FIG.10( b), respectively, are front and back views of substrate 5 of anacoustic touch sensor, according to a further specific embodiment. Aswas the case with FIGS. 2( a) and 2(b), transducers 35 in FIGS. 8( a),9(a) and 10(a) are shown in dotted line to provide a frame of reference,respectively, in relation to FIGS. 8( b), 9(b) and 10(b), which are planviews of back surface 15 of the acoustic touch sensor where transducers35 are shown in solid line. To provide a further frame of reference, X-Ycoordinate axes and, where relevant, U-coordinate axis are shown inFIGS. 8( a), 8(b), 9(a), 9(b), 10(a) and 10(b). The U-coordinate is acoordinate in the same plane as X and Y but in a tilted direction.Measuring X, Y and U coordinates of touches provides a degree ofredundancy in position measurement that is needed for high performancedual touch or multiple simultaneous touch applications. As will bediscussed below, the addition of U-coordinate measurement capabilityprovides additional benefits for bezel-less acoustic touch devices.

FIG. 8( a) and FIG. 8( b), respectively, are front and back views ofsubstrate 5 of an acoustic touch sensor, according to a specificembodiment of the invention. The embodiment of FIGS. 8( a) and 8(b) isstructurally similar to, and operates similarly for detecting a touch innominal touch region 13 as described above for FIGS. 2( a) and 2(b).Additional aspects of the specific embodiment of FIGS. 8( a) and 8(b)will be described. In this specific embodiment, unlike the embodiment ofFIGS. 2( a) and 2(b), four beam splitters 75 are provided on frontsurface of substrate 5. The specific embodiment of FIGS. 8( a) and 8(b)therefore uses the U-coordinate axis to provide an XYU surface acousticwave touch sensor capable of reliably detecting multiple touches onnominal touch region 13, on peripheral region 14 external to nominaltouch region 13 on front surface, and/or touches on the curvedconnecting surface 20. Edge sensitive touch functions may be implementedon peripheral region 14 and/or curved connecting surface 20.

As seen in FIGS. 8( a) and 8(b), beam splitters 75 deflect a portion ofthe incident surface acoustic wave beam in a direction perpendicular tothe U-coordinate axis while leaving another portion undeflected. Beamsplitter 75 may be fabricated on front surface of substrate 5 by, forexample, screen printing glass frit or composite polymer material inks,or alternatively by etching grooves. Each beam splitter 75 has multipledeflecting elements, which may be parallel reflector segments that arerotated by a defined angle (for a predefined aspect ratio system, suchas a 4:3 aspect ratio) with respect to vertical and spaced along theaxis of the beam splitter with a center-to-center spacing of the surfaceacoustic wavelength divided by the sine of the difference of 90 degreesand the defined angle. The deflecting elements of top and bottom beamsplitters 75 b and 75 c have a first defined angle, and the deflectingelements of side beam splitters 75 a and 75 d have a second definedangle (different than the first defined angle). The acoustic waveincident on the beam splitter deflecting element is coherently deflectedat a predetermined angle relative to the axis of the beam splitter,where the angle of reflection equals the angle of incidence. It shouldbe recognized that the beam splitter's deflecting element angle can bevaried for other embodiments, depending on the geometry of the substratedimensions and aspect ratio, and further details regarding such acousticwave beam splitters may be found in connection with at least FIGS. 4-6of U.S. Patent Application Publication 2008/0266266A1, the entirety ofwhich is incorporated by reference herein. An angle perpendicular to thepredefined angle of the deflecting elements of beam splitters 75 a and75 d defines the U-coordinate axis.

It is noted that some specific embodiments having exposed beam splitters75 on front surface 10 of substrate 5 may be cosmetically undesired andlead to durability or wear issues. If lead-based ceramic frits are used,there is also a risk that exposed frits of beam splitters 75 may bedissolved by acids such as acidic soft drinks and potentially exposeusers to lead poisoning. If beam splitters 75 are fabricated oflead-based frits it may be desirable that they be covered with asealant. Alternatively non-lead based materials may be used includingcomposite polymer inks or non-lead-based higher cure temperaturematerial frits and ablated grooves which optimally are backfilled with afrit or other material.

In operation, the portion of surface acoustic beam reflected fromtransmitting transducer 35 a by array 40 a traveling around curvedconnecting surface 20 to be incident on beam splitter 75 a getspartially deflected (U1 beam) along a line of a constant coordinate U,while the undeflected portion proceeds as previously described to detectthe Y-axis coordinate of a touch. As seen by the dotted line arrowsindicating the U sensing wave travel paths in FIGS. 8( a) and 8(b), thepartially deflected portion of the U1 beam travels along the line ofthat constant coordinate U on front surface 10 and is incident on beamsplitter 75 b, which deflects the portion of the beam around curvedconnecting surface 20 to back surface 15 where reflecting array 40 dreflects the beam portion to receiving transducer 35 d. Thus, receivingtransducer 35 d also acts as U1-signal receiving transducer, in additionto acting as X-coordinate signal receiving transducer. The U1 signalmeasures the U coordinate for one portion of the touch area.

Similarly, the portion of surface acoustic beam reflected fromtransmitting transducer 35 b by array 40 c traveling around curvedconnecting surface 20 to be incident on beam splitter 75 c getspartially deflected (U2 beam) along a line of constant coordinate U,while the undeflected portion proceeds as previously described to detectthe X-axis coordinate of a touch. As seen by the dotted line arrowsindicating the U sensing wave travel paths in FIGS. 8( a) and 8(b), thepartially deflected portion of the U2 beam travels along the line ofconstant coordinate U on front surface 10 and is incident on beamsplitter 75 d, which deflects the portion of the beam around curvedconnecting surface 20 to back surface 15 where reflecting array 40 breflects the beam portion to receiving transducer 35 c. Thus, receivingtransducer 35 c also acts as U2-signal receiving transducer, in additionto acting as the Y-coordinate signal receiving transducer. The U2 signalmeasures the U coordinate for a portion of the touch area not covered bythe signal U1.

The system controller analyzes the received signals along the time base,to detect indicated coordinates of the touch (which occurs where thetravel paths shown in FIG. 2( a) intersect) within nominal touch region13 on front surface 10. Further, the system controller analyzes thereceived signals along the time base, to detect indicated coordinates ofany touch that occurs on peripheral region 14 on front surface 10 or onconnecting surface 20 based on the travel paths shown in FIGS. 8( a) and8(b). Thus, the use of the U-coordinate signal not only providescoordinate measurement redundancy for robust multiple touch operations,but also enables the device controller to distinguish edge sensitivetouch functions that may be provided.

FIG. 9( a) and FIG. 9( b), respectively, are front and back views ofsubstrate 5 of an acoustic touch sensor, according to further specificembodiments of the invention. The embodiment of FIGS. 9( a) and 9(b) isstructurally similar to, and operates similarly for detecting a touch innominal touch region 13 as, the embodiment described above for FIGS. 2(a) and 2(b), and that description will not be repeated. Instead,additional aspects of the specific embodiment of FIGS. 9( a) and 9(b)will be described. To provide a further frame of reference, X-Y-Ucoordinate axes are shown in FIGS. 9( a) and 9(b). In this specificembodiment, unlike the embodiment of FIGS. 2( a) and 2(b) and FIGS. 8(a) and 8(b), four beam splitters 85 are provided on back surface 15 ofsubstrate 5. The specific embodiment of FIGS. 9( a) and 9(b) thereforeprovides another example of an XYU surface acoustic wave touch sensorcapable of reliably detecting multiple touches on nominal touch region13 and distinguishing touches on curved connecting surfaces 20 orperipheral region 14 that may be provided with touch input edgefunctions such as described above.

Similar to beam splitters 75 discussed above, beam splitters 85 deflecta portion of the incident surface acoustic wave beam in the U directionwhile leaving another portion undeflected. According to this specificembodiment, beam splitters 85 may be fabricated on back surface 15(directly without layer 60 or via layer 60, according to variousembodiments) of substrate 5. With specific embodiments having beamsplitters 85 on back surface 15, there are no cosmetic issues withvisibility and no durability and/or safety concerns, as the exposed beamsplitter frits are protected within and by housing 55.

In operation, the portion of surface acoustic beam reflected fromtransmitting transducer 35 a by array 40 a is incident in the negative(−) X-direction on beam splitter 85 a, is partially deflected (U1 beam)and travels around curved connecting surface 20 along a line of constantU, while the undeflected portion proceeds as previously described todetect the Y-axis coordinate of a touch. As seen by the dotted linearrows indicating the U sensing wave travel paths in FIGS. 9( a) and9(b), the partially deflected portion of the U1 beam travels along theline of constant value U on front surface 10 and travels around curvedconnecting surface 20 to back surface 15, to be incident on beamsplitter 85 b, which deflects the portion of the beam in the negative(−) Y-direction to reflecting array 40 d which reflects the beam portionin the positive (+) X-direction to receiving transducer 35 d. Thus,receiving transducer 35 d also acts as U1-signal receiving transducer,in addition to acting as X-coordinate signal receiving transducer.

Similarly, the portion of surface acoustic beam reflected fromtransmitting transducer 35 b by array 40 c is incident in the negative(−) Y-direction on beam splitter 85 c, is partially deflected (U2 beam)and travels around curved connecting surface 20 along a line of constantvalue U, while the undeflected portion proceeds as previously describedto detect the X-axis coordinate of a touch. As seen by the dotted linearrows indicating the U sensing wave travel paths in FIGS. 9( a) and9(b), the partially deflected portion of the U2 beam travels along theline of constant value U on front surface 10 and travels around curvedconnecting surface 20 to back surface 15, to be incident on beamsplitter 85 d, which deflects the portion of the beam in the negative(−) X-direction to reflecting array 40 b which reflects the beam portionin the positive (+) X-direction to receiving transducer 35 c. Thus,receiving transducer 35 c also acts as U2-signal receiving transducer,in addition to acting as Y-coordinate signal receiving transducer.

The system controller analyzes the received signals along the time base,to detect indicated coordinates of the touch (which occurs where thetravel paths shown in FIG. 2( a) intersect) within nominal touch region13 on front surface. Further, the system controller analyzes thereceived signals along the time base, to detect indicated coordinates ofany touch that occurs on peripheral region 14 on front surface 10 or onconnecting surface 20 based on the travel paths shown in FIGS. 9( a) and9(b).

Further details on various types of XYU-type touch sensors aredescribed, for example, in the disclosures of U.S. Pat. No. 5,854,450and U.S. Published Patent Application 2008/0266266, which areincorporated by reference. With another example of an Adler-typeacoustic touch sensor, folded acoustic paths may be used in order tofurther reduce the number of transducers, such as described in U.S. Pat.Nos. 4,700,176; 5,072,427; 5,162,618; and 5,177,327; each of which isincorporated herein by reference. It should be recognized that thepresent invention may be generalized to these different types ofXYU-type touch sensors and/or touch sensors having reduced numbers oftransducers. For example, an XYU-type touch sensor having a U arraysuperposed on the X-Y reflective element arrays, or an XYU-type touchsensor having separate reflective arrays and adjacent beam splitters,may be used in specific embodiments of the invention.

FIG. 10( a) and FIG. 10( b), respectively, are front and back views ofsubstrate 5 of an acoustic touch sensor, according to still furtherspecific embodiments of the invention. The embodiment of FIGS. 10( a)and 10(b) is structurally similar to, and operates similarly fordetecting a touch in nominal touch region 13 as, the embodimentdescribed above for FIGS. 2( a) and 2(b). Additional aspects of thespecific embodiment of FIGS. 10( a) and 10(b) will be described. Toprovide a further frame of reference, X-Y-U coordinate axes are shown inFIGS. 10( a) and 10(b). In this specific embodiment, unlike theembodiment of FIGS. 2( a) and 2(b) and FIGS. 9( a) and 9(b), only twobeam splitters 85 are provided on back surface 15 of substrate 5. Thespecific embodiment of FIGS. 10( a) and 10(b) therefore provides an XYsurface acoustic wave touch sensor capable of detecting touches innominal touch region 13 and distinguishing touches on curved connectingsurface 20 and/or peripheral region 14 that may be provided with edgesensitive touch functions described above.

According to this specific embodiment, only two beam splitters 85 arefabricated on back surface 15 (directly without layer 60 or via layer60, according to various embodiments) of substrate 5.

In operation, the portion of surface acoustic beam reflected fromtransmitting transducer 35 a by array 40 a travels in the negative (−)X-direction, travels around curved connecting surface 20, and proceedsas previously described to detect the Y-axis coordinate of a touch. Asseen by the dotted line arrows indicating the U sensing wave travelpaths in FIGS. 10( a) and 10(b), two U beams (similar to the U2 beamdescribed for FIGS. 9( a) and 9(b)) but with different U values), inorder to show the general range of U values along bottom curvedconnecting surface 20 a and the side curved connecting surface 20 b. Theportion of surface acoustic beam reflected from transmitting transducer35 b by array 40 c is incident in the negative (−) Y-direction on beamsplitter 85 c, is partially deflected and travels around curvedconnecting surface 20 a along a line of constant value U, while theundeflected portion proceeds as previously described to detect theX-axis coordinate of a touch. The partially deflected portion of U beamtravels along the line of constant value U on front surface 10 andtravels around curved connecting surface 20 b to back surface 15, to beincident on beam splitter 85 d, which deflects the portion of the beamin the negative (−) X-direction to reflecting array 40 b which reflectsthe beam portion in the positive (+) X-direction to receiving transducer35 c. Thus, receiving transducer 35 c also acts as the U-coordinatesignal receiving transducer, in addition to acting as Y-coordinatesignal receiving transducer.

The system controller analyzes the received signals along the time base,to detect indicated coordinates of the touch (which occurs where thetravel paths shown in FIG. 2( a) intersect) within nominal touch region13 on front surface. Further, the system controller can analyze thereceived signals along the time base, to detect indicated coordinates ofany touch that occurs on peripheral region 14 a and/or 14 b on frontsurface 10 or on connecting surface 20 a and/or 20 b, based on thetravel paths shown in FIGS. 10( a) and 10(b). In particular, thepresence of the U signal on surface 20 a or region 14 a in connectionwith only a detected X-coordinate signal (i.e., no detected Y-coordinatesignal) will enable edge sensitive touch functions where the U signal ispresent. If there is an absence of the U signal on surface 20 or region14 a in connection with only the detected X-coordinate signal, then thedevice controller will be able to distinguish edge sensitive touchfunctions as being those on region 14 d or surface 20 d. The devicesimilarly can distinguish edge sensitive touch functions detected asbeing on either region 14 b or 20 b, from those of region 14 c or 20 c,by using absence or presence of the U signal in connection with only aY-coordinate signal (i.e., no detected X-coordinate signal) beingdetected.

Of course, it should be recognized that in other embodiments, the use oftwo beam splitters (85 b and 85 a, as seen in FIG. 9( b)) on backsurface 15 may differ from those (85 c and 85 d) shown in FIGS. 10( a)and 10(b) so that certain curved connecting surfaces 20 (opposite from20 a and 20 b) and their respectively proximate portions of peripheralregion 14 may be distinguished to provide the edge sensitive touchdetection functions.

Further, it should be recognized that the embodiment of FIGS. 8( a)-8(b)having four beam splitters on front surface 10 can be altered for stillanother embodiment that has two beam splitters (either 75 a and 75 b, or75 c and 75 d) on front surface 10 (in a similar manner as theembodiment of FIGS. 10( a)-10(b) used two beam splitters (85 c and 85 d)on back surface 15) in order to provide edge sensitive touch functionsin another example of an XY sensor. It also should be recognized thathaving beam splitters that extend only partially along the peripheralcorner edge of the sensor (for example, 85 d and 85 c being truncated sothat there are only parts of 85 d and 85 c closest to the corner neartransducer 35 b that are formed), and not along the entire length ofproximate reflect arrays, would merely result in the edge sensitivetouch function parts of region 14 and/or surfaces 20 a and 20 b beingspatially limited to regions indicated by brackets 87, in accordancewith another specific embodiment. This would be similarly the case ifthe beam splitters 75 d and 75 c were formed similarly truncated in theembodiment shown in FIGS. 8( a) and 8(b). That is, the edge sensitivetouch functions would be limited spatially to the bottom right corner ofperipheral region 14 and connecting surface 20, such as shown in FIG. 7.In yet another embodiment, it is possible to modify the embodiments ofFIG. 8, 9 or 10 to use only one beam splitter 75 or 85 along one edge(e.g., top, left, right or bottom) of substrate 5, such that at leastone peripheral region 13 and/or its corresponding curved connectingsurface 20 are provided with edge sensitive touch functions.

For simplicity of discussion for FIG. 7, the edge sensitive touchfunctions described and/or shown are illustrated as being on side curvedconnecting surface 20 b and bottom curved connecting surface 20 a and/oron those portions of peripheral region 14 proximate to 20 a and 20 b.However, it should be emphasized that device 50 can have the edgesensitive touch function capability available anywhere on curvedconnecting surface 20 and/or on peripheral region 14, according tovarious specific embodiments. This is because the U-coordinate signal isused in conjunction with either the X-coordinate or the Y-coordinate todetermine the touch input applied to any edge sensitive functions.

FIGS. 11( a), 11(b), 11(c) and 11(d) illustrate another specificembodiment for an acoustic XY sensor that resolves the ambiguity issuein portions of peripheral region 14 (but not curved connecting surface20). This embodiment does not measure a U-coordinate, but rather extendsthe X-coordinate or Y-coordinate signals for detecting touches intoportions of peripheral region 14. This specific embodiment changes theplacement of reflective arrays 40 and transducers 35 from those shown inFIGS. 2( a) and 2(b). In particular, transducers 35 a and 35 c are movedin the negative (−) Y-axis direction, transducers 35 b and 35 d aremoved in the negative (−) X-axis direction. Further, reflecting array 40d is extended over transducer 35 a, reflective array 40 b is extended tobe behind transducer 35 b, and reflective arrays 40 a and 40 c areextended to join at their intersecting corner. That is, there is areflector element common to two reflective arrays.

In detecting XY data for a touch in nominal touch region 13, thisspecific embodiment shown in FIGS. 11( a)-11(d) operates similarly asalready described for FIGS. 2( a)-2(b) and that description is notrepeated here. FIGS. 11( a) and 11(b) are useful to describe theoperation of a touch to the edge sensitive functions on peripheralregion 14 a (a touch on curved connecting surface 20 a remains ambiguousas it produces the same signal as a touch on the top portion of curvedconnecting surface 20). FIGS. 11( a) and 11(b) show the possibleacoustic wave travel paths (solid line arrows) for detecting anX-coordinate of a touch on nominal touch region 13 (similar to thatshown in FIG. 2( a)) and an X-coordinate for a touch on peripheralregion 14 b. In particular, surface acoustic waves travel fromtransmitting transducer 35 b along the negative (−) X-axis direction onwhich reflecting array 40 c is provided near a peripheral edge of backsurface 15 of substrate 5. As seen by the solid line arrows indicatingthe X-coordinate sensing wave travel paths in FIGS. 11( a) and 11(b),reflective array 40 c couples or reflects part of the acoustic waveswith a sensing wave: traveling from reflective array 40 c outwardlyalong the negative (−) Y-axis direction toward and around the proximateconnecting surface 20 a of substrate 5, traveling along the positive (+)Y-axis direction across front surface, traveling toward and around theopposing curved connecting surface 20 toward in a negative (−) Y-axisdirection reflective array 40 d on back surface 15, and traveling alongreflective array 40 d in a positive (+) X-axis direction to receivingtransducer 35 d.

FIGS. 11( c) and 11(d) are useful to describe the operation of a touchto the edge sensitive functions on peripheral region 14 b. (A touch oncurved connecting surface 20 b remains ambiguous as it produces the samesignal as a touch on the opposite portion of curved connecting surface20.) FIGS. 11( c) and 11(d) show the possible acoustic wave travel paths(solid line arrows) for detecting a Y-coordinate of a touch on nominaltouch region 13 (similar to that shown in FIG. 2( a)) and a Y-coordinatefor a touch on peripheral region 14 b. In particular, surface acousticwaves travel from transmitting transducer 35 a along the negative (−)Y-axis direction on which reflecting array 40 a is provided near aperipheral edge of back surface 15 of substrate 5. As seen by the solidline arrows indicating the Y-coordinate sensing wave travel paths inFIGS. 11( c) and 11(d), reflective array 40 a reflects part of theacoustic waves with a sensing wave: traveling from reflective array 40 aoutwardly along the negative (−) X-axis direction toward and around theproximate connecting surface 20 b of substrate 5, traveling along thepositive (+) X-axis direction across front surface, traveling toward andaround the opposing curved connecting surface 20 to be incident in anegative (−) X-axis direction on reflective array 40 b on back surface15, and traveling along reflective array 40 b in a positive (+) Y-axisdirection to receiving transducer 35 c.

The system controller analyzes the received signals along the time base,to detect indicated coordinates of the touch (which occurs where thetravel paths shown in FIG. 2( a) intersect) within nominal touch region13 on front surface. The system controller also analyzes the receivedsignals along the time base, to detect indicated coordinates of anytouch that occurs on peripheral region 14 a and/or 14 b on front surface10, or on connecting surface 20 a and/or 20 b, based on the travel pathsshown in FIGS. 11( a)-11(d).

Therefore, the specific embodiment illustrated in FIGS. 11( a)-11(d)results in peripheral region 14 a and/or peripheral region 14 b (belowand to the left of dotted lines 100) which are outside of nominal touchregion 13 being capable of processing edge sensitive touch functions.

FIG. 12( a) and FIG. 12( b) illustrate another specific embodiment foran acoustic XY sensor having additional coordinate or position data touse in conjunction with the X-coordinate or Y-coordinate associated withthe acoustically detected touch in peripheral region 14 and/or on curvedconnecting surface 20. This specific embodiment does not change theplacement of reflective arrays 40 and transducers 35 from those shown inFIGS. 2( a) and 2(b), but instead adds one or more of a sensingelectrode layer 103 to provide the additional position data. Indetecting XY data for a touch in nominal touch region 13, this specificembodiment shown in FIGS. 12( a)-12(b) operates similarly as alreadydescribed for FIGS. 2( a)-2(b) and that description is not repeatedhere.

Sensing electrodes 103 on device 50 sense the change in capacitance (orohmic resistance in some embodiments) resulting from a touch that ismade in peripheral region 14 and/or on connecting surface 20 providesthe additional position data that is used in conjunction with theacoustically detected touch to provide edge sensitive touch functions.That is, electrode layer 103 may be used as a capacitive sensingelectrode in some embodiments, and in other embodiments electrode layer103 may be used as an ohmic sensing electrode.

According to specific embodiments, a possible layout of sensingelectrode layers 103 are merely shown (in dotted outline) according tospecific embodiments in FIG. 12( a). Although electrode layers 103 areshown as being on front surface 10 of FIG. 12( a), it should be notedthat this may be the case only in some specific embodiments. In suchembodiments where sensing electrode layer 103 is on front surface 10,layer 103 (usable as either a capacitive or ohmic sensing electrode)preferably is transparent, such as indium tin oxide (ITO), or otherknown transparent conductive material that may be screen printed orsputtered onto front surface 10. In other embodiments, layer 103 (usedas capacitive sensing electrodes) may be directly (or via layer 60) onback surface 15 so as to be between substrate 5 andtransducers/arrays/beam splitters thereon. If layer 60 is not used, thenelectrode layer 103 may be a transparent conductive material, but iflayer 60 is used, then electrode layer 103 may be opaque and any type ofconductive material that is acoustically benign, such asmetal-containing material, that may be screen printed or sputtered ontolayer 60. In another specific embodiment where electrode 103 is formedon layer 60 on back surface 10 of substrate 5, as shown in FIG. 12( c),which is a magnified partial plan view of a corner of back surface 15 ofsubstrate 5, the reflecting elements 125 of reflecting array 20 (beamsplitters 85 may be used, but are not shown in this figure forsimplicity) are coupled together with at least a conductive lead 127. Inthis embodiment, the silver-containing glass frits 125 of array 20 servenot only as the reflective array but also, with the lead 127, aselectrode 103 (indicated by the dotted-dash line) used for capacitivesensing. Lead 127 may be any conductive material that is acousticallybenign, such as a thin line of the same material used to fabricate thereflecting elements 125. In another similar embodiment, reflectingelements 125 of reflective array 20 are coupled together with conductivelead 127 and optionally another similar lead (not shown) along theopposite end of reflecting elements 125.

Although four electrodes 103 a, 103 b, 103 c and 103 d are shown in FIG.12( a), it should be recognized that having two capacitive electrodes(103 a and 103 b, or 103 a and 103 d, or 103 b and 103 c, or 103 d and103 c) will be sufficient to provide the additional position data neededto address the ambiguity issue for providing edge sensitive touchfunctions on connecting surface 20 and/or peripheral region 14. In someembodiments, use of at least one electrode (for capacitive or ohmicsensing) is possible where only one peripheral region 13 and/or itscorresponding curved connecting surface 20 is provided with edgesensitive touch functions, and some embodiments may have more than fourcapacitive electrodes 103 by splitting the electrodes 103 into smallersizes, although the electrical connecting scheme for these electrodes103 would become more complicated. It also should be recognized thathaving two capacitive electrodes 103 that extend only partially alongthe peripheral corner edge of the sensor (for example, 103 a and 103 bbeing truncated so that there are only parts of 103 a and 103 b closestto the corner near transducer 35 b that are formed), and not along theentire peripheral edge of the sensor would merely result in the edgesensitive touch functional parts of region 14 and/or surfaces 20 a and20 b being spatially limited to regions indicated by brackets 105, inaccordance with another specific embodiment.

The system controller analyzes the received signals along the time base,to detect indicated coordinates of the touch (which occurs where thetravel paths shown in FIG. 2( a) intersect) within nominal touch region13 on front surface. For touches outside of nominal touch region 13,touches are detected and unambiguously recognized as top, bottom, leftor right touches through a combination of acoustic and capacitive (orohmic) measurements. The system controller, which is also coupled to thecapacitive electrodes 103, analyzes the received signals to detect thepresence of a touch proximate to any of the electrodes 103 indicating atouch with coordinates in peripheral region 14 on front surface 10and/or on connecting surface 20. This determines whether the touch istop, bottom, right or left oriented. The coordinate along the selectedperimeter sides is based on the acoustic beam travel paths shown inFIGS. 11( a)-11(d).

Various aspects of acoustic touch sensor devices according to specificembodiments of the invention have been described and shown. Manychanges, modifications, variations, combinations, subcombinations andother uses and applications of the subject invention will, however,become apparent to those skilled in the art after considering thisspecification and the accompanying drawings which disclose the preferredembodiments thereof. For example, although the embodiments in thefigures show curved connecting surface 20 as extending along the entireperiphery of substrate 5, in other embodiments there may be two curvedconnecting surfaces 20 opposite each other when edge sensitive touchfunctions are only provided on up to two corresponding peripheralregions 14 and/or on up to two corresponding curved connecting surfaces20. As another example, curved connecting surface 20 may be formed alongmost of the edge of substrate 5 except at corners, at which frontsurface 10 and back surface 15 are connected by sharp edges where cornerbezel-like covers may be used. In another specific embodiment, substrate5—having one transducer 35 (acting as both transmitter and receiver) andone reflecting array 40 formed on back surface 15—may have one curvedconnecting surface 20 provided opposite a sharp edged surface such thatthe transmitted surface acoustic waves from transducer 35 get reflectedby reflecting array 40, travel around curved connecting surface 20 andacross front surface 10, get reflected off the sharp edged surface,travel back across front surface 10 and around curved connecting surface20, and get reflected by reflecting array 40 back to transducer 35 whichreceives the surface acoustic waves. In such an embodiment, edgesensitive touch functions might be provided only along one peripheralregion 13 and/or its one corresponding curved connecting surface 20.

These and other changes, modifications, variations and other uses andapplications, according to various specific embodiments, which do notdepart from the spirit and scope of the invention are deemed to becovered, and limited only by the claims.

1. An acoustic touch apparatus, comprising: a substrate capable ofpropagating surface acoustic waves, said substrate having a frontsurface, a back surface, and a curved connecting surface formed betweensaid front surface and said back surface; and at least one acoustic wavetransducer and at least one reflective array, said acoustic wavetransducer and said reflective array behind said back surface, saidacoustic wave transducer capable of transmitting or receiving surfaceacoustic waves to or from said reflective array, and said reflectivearray is capable of acoustically coupling said surface acoustic waves topropagate between said back surface and said front surface via saidcurved connecting surface.
 2. The apparatus according to claim 1,wherein said front surface includes a nominal touch region and aperipheral region external to said nominal touch region; and saidapparatus further comprising: a controller determining a coordinate of atouch on said nominal touch region, on said peripheral region or on saidcurved connecting surface, based on detected waveform perturbations ofsaid surface acoustic waves, said controller electrically coupled tosaid acoustic wave transducer; a display behind said back surface; andwherein said peripheral region is not covered by a bezel.
 3. Theapparatus according to claim 2, wherein said controller upon determiningsaid coordinate of said touch on said peripheral region or on saidcurved connecting surface generates touch coordinate data for saidperipheral region or said curved connecting surface.
 4. The apparatusaccording to claim 3, wherein said touch coordinate data initiates anedge sensitive touch function of said apparatus.
 5. The apparatusaccording to claim 4, wherein said apparatus is provided with aplurality of edge sensitive touch functions corresponding to differentcoordinates on said peripheral region or on said curved connectingsurface.
 6. The apparatus according to claim 1, further comprising atleast one beam splitter.
 7. The apparatus according to claim 6, whereinsaid beam splitter is behind said back surface.
 8. The apparatusaccording to claim 1, wherein said substrate has a thickness T and saidcurved connecting surface joins said front surface and said back surfacevia at least one curved section having a radius R ranging between aboutT/3 and about T/16.
 9. The apparatus according to claim 1, wherein saidacoustic wave transducer and said reflective array are coupled to saidback surface via an acoustically benign layer on said back surface. 10.The apparatus according to claim 1, wherein said acoustically benignlayer comprises an inorganic material.
 11. The apparatus according toclaim 10, wherein said acoustically benign layer is opaque ortranslucent.
 12. The apparatus according to claim 3, wherein saidacoustic wave transducer and said reflective array are coupled to saidback surface via an acoustically benign layer on said back surface, saidacoustically benign layer providing an icon indicating said edge touchsensitive function.
 13. The apparatus according to claim 7, wherein saidacoustic wave transducers, said reflective arrays and said beam splitterare coupled to said back surface via an acoustically benign layer onsaid back surface.
 14. The apparatus according to claim 3, wherein saidedge sensitive touch function comprises an input action initiated bydetermining a gesture is occurring.
 15. The apparatus according to claim1, further comprising: at least one conductive electrode disposed nearsaid peripheral region or said curved connecting surface.
 16. Theapparatus according to claim 15, wherein said at least one conductiveelectrode is behind said back surface.
 17. The apparatus according toclaim 16, wherein said at least one conductive electrode comprisesreflective elements of said reflective array and a conductive leadcoupling said reflective elements, wherein said at least one conductiveelectrode and said reflective elements are formed on said back surfacevia an acoustically benign layer.
 18. The apparatus according to claim1, further comprising a second reflective array, wherein said secondreflective array and said at least one reflecting array share a commonreflector element.
 19. An acoustic touch apparatus, comprising: asubstrate capable of propagating surface acoustic waves, said substratehaving a front surface, a back surface, and a curved connecting surfaceformed between said front surface and said back surface, wherein saidfront surface includes a nominal touch region and a peripheral regionexternal to said nominal touch region, said peripheral region notcovered by a bezel; at least one acoustic wave transducer and at leastone reflective array, said acoustic wave transducer and said reflectivearray coupled to said back surface via an acoustically benign layer onsaid back surface, said acoustic wave transducer capable of transmittingor receiving surface acoustic waves to or from said reflective array,and said reflective array is capable of acoustically coupling saidsurface acoustic waves to propagate between said back surface and saidfront surface via said curved connecting surface; a controllerdetermining a coordinate of a touch on said nominal touch region, onsaid peripheral region or on said curved connecting surface, based ondetected waveform perturbations of said surface acoustic waves, saidcontroller electrically coupled to said acoustic wave transducer; and adisplay disposed behind said back surface.
 20. An acoustic touchapparatus, comprising: a substrate capable of propagating surfaceacoustic waves, said substrate having a front surface, a back surface,and a curved connecting surface formed between said front surface andsaid back surface, wherein said front surface includes a nominal touchregion and a peripheral region external to said nominal touch region,said peripheral region not covered by a bezel; at least one acousticwave transducer and at least one reflective array, said acoustic wavetransducer and said reflective array coupled to said back surface via anacoustically benign layer on said back surface, said acoustic wavetransducer capable of transmitting or receiving surface acoustic wavesto or from said reflective array, and said reflective array is capableof acoustically coupling said surface acoustic waves to propagatebetween said back surface and said front surface via said curvedconnecting surface; a controller determining a coordinate of a touch onsaid nominal touch region, on said peripheral region or on said curvedconnecting surface, based on detected waveform perturbations of saidsurface acoustic waves, said controller electrically coupled to saidacoustic wave transducer, wherein said controller upon determining saidcoordinate of said touch on said peripheral region or on said curvedconnecting surface generates touch coordinate data for said peripheralregion or said curved connecting surface.
 21. The apparatus according toclaim 2, wherein said display is mounted behind said back surface via abracket and within a housing, said housing not having said bezel. 22.The apparatus according to claim 9, wherein said substrate has athickness T and at least said curved connecting surface is coupledbetween said front surface and said back surface, said curved connectingsurface having a radius R of about 2.7λ.
 23. The apparatus according toclaim 1, wherein said curved connecting surface is coupled between saidfront surface or said back surface via at least one flat portion. 24.The apparatus according to claim 23, wherein said at least one flatportion forms an angle of less than 8 degrees from either said frontsurface or said back surface.
 25. The apparatus according to claim 1,wherein said curved connecting surface comprises two curved portionscoupled with at least one flat portion between said two curved portions.26. The apparatus according to claim 21, wherein said housing is coupledto said back surface of said substrate via a gasket with a wiper bladecross section.
 27. The apparatus according to claim 2, furthercomprising first bracket, a spring bracket, and a gasket with a wiperblade cross section and having a minimal portion in contact with saidsubstrate, said first bracket coupled between said back surface and afirst side of said gasket, said spring bracket coupled to a second sideof said gasket and a bottom surface of said first bracket such that saidgasket provides a pressure seal between said substrate and a framesurrounding said substrate.
 28. The apparatus according to claim 27,wherein said display is mounted behind said back surface using a thirdbracket connected to a fourth bracket, said third bracket connected tosaid frame, said fourth bracket fastened to said spring bracket and saidfirst bracket.
 29. The apparatus according to claim 28, wherein aportion of said gasket is above of a perimeter of said frame.
 30. Theapparatus according to claim 19, wherein an acoustically attenuating andoptically transparent layer is disposed between said back surface andsaid display.